THE ROLE OF CAMP IN THE TOPOGRAPHIC ORGANIZATION OF THE OLFACTORY SYSTEM

Abstract

The article analyzes the literature data on the role of molecular olfactory receptors (OR) and cAMP in the formation of the topographic organization of the olfactory sensory system. Before its transmission to the brain, sensory information is already organized in the peripheral region according to the “one neuron–one receptor” principle, which also extends to the glomeruli in the olfactory bulb, which obey the “one glomerulus–one receptor” law. At present, an important role in the formation of the sensory map has been attributed to ORs, which plays a dual role in the organization of the olfactory system, since they are localized both in the olfactory cilia (OC) and in the membrane of the axon growth cone of the same olfactory sensory neuron (OSN), and determine the target for the axons of the OSN in the olfactory bulb (OB). However, there is strong evidence for the central role of the intracellular cAMP signaling system in sensory map development. Using the method of genetic mutation with the abolition of cAMP synthesis, it was revealed that the axons carrying this mutation never penetrate the glomerular layer, but remain in the layer of the olfactory nerve. At the same time, OSN axons target the OB but fail to form distinct and well-defined glomeruli, many of which become heterogeneous because they contain fibers belonging to OSNs expressing ORs for different odorants. Thus, cAMP synthesized in the tip of the RSN axon, under the action of signals from the OB, regulates the expression of molecules of its navigation to its target in the OB, and also forms intrabulbar chemical and electrical synapses, forming neuronal circuits. Numerous clinical and experimental data have led to the conclusion that the pathogenetic mechanisms of the development of some psychiatric diseases are associated with dysregulation of cAMP.